other big story of the day, gun control, gun reform, and an apparent breakthrough. A rare compromise deal on background checks of people buying guns. An emotional plea from the first lady. But first david muir shows us what would change if this deal passes. A group of senators have come up with a compromise saying if you buy a gun at a gun show or one online, have you to undergo a background checks. Right now in 30 states, you can buy from a private seller, no questions asked. Tonight we put it to the test again because it's at the center of a red hot debate. Omar samaha, a young man abc news has been following since the massacre at virginia tech. Omar lost his sister reema. Afterward, lawmakers promised to close the gun loophole. We went with him a year later, wanted to know how many guns he could buy in one hour, no questions asked. We gave him $5,000. Already approached by a seller. Omar buys a gun. This is a glock. Reporter: You bought this before you got in the show? Yeah, he was sitting right outside the door. How much you want? 450 bucks. Here's the cash. See you later. That was it. Reporter: A glock handgun, the same kind used to kill his sister. Inside he makes his way through the aisles when he emernls, he's carrying a semault weapon. What did they ask? Nothing. Reporter: In the next hour, he emerges over and over again. I got more than I can even hold. Reporter: Watching the entire time, a atf agent. These sellers did what they're legally able to do. Nothing illegal about their transactions. Reporter: And tonight nearly six years to the day after virginia tech, after omar lost his sister, we check back in, asking if this proposal passed, would visiting that gun show be different? It would be different. I would have to undergo a background check for every gun i bought. I bought every one of those guns without a background check. Tonight omar knows it's not a done deal. There are many who believe in this country, it's the wrong move. The nra saying expanding background checks will not prevent the next shooting and will not keep our kids safe in schools. They point to our fa health system. They say that's what we should concentrate on, not the gun shows. Thank you, david. I want to get a status report on what is going to happen. What is likely to happen. So let's bring in abc's white house correspondent jonathan karl. Jon, is it going to pass, do you think and how soon could it happen? This greatly improves the chances of something passing. This is the very first bipartisan agreement, I would say it has a 55% chance of passing. Not more than that, remember it still has to get through the republican. Controlled house. The earliest that can happen would be this summer. Joining the push to get something passed is the first lady. She was in chicago today making a very rare appeal to pass this gun control proposal and getting emotion when she talked about the teenager shot and killed a week after she performed at the inauguration. It is hard to know what to say to a room full of teenagers who are about to bury their best friend. But I by telling them that hidea was clearly on her way to doing something truly worthy with her life. Again, as you say, jon, it is rare to see her out on an issue like this one. Let me ask y, if this passes will the administration come back on banning assault weapons and high capacity magazines. They will push for that. But either one of them stands any chance at all of getting through the congress, no chance at all in the house. The only thing that has a chance of passing is this background check issue. All right, some possible movement. Thanks so much, jon karl.

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